Decoupling the ADC input

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R!f@@

Joined Apr 2, 2009
9,918
I salvaged a PS3 joystick. It's crappy. The Joy part get's stuck sometimes but I think it would do for testing the program.

About decoupling. I am putting a 10μf across the 5V at the Joystick PCB decoupled with a 100nf.

The center pin of the VR is also decoupled to ground with a 100nF.

Question is, will these caps be enough ?

The VR is used as ADC input.
 

t06afre

Joined May 11, 2009
5,934
Puting a "decoupling" cap across the ADC input. Will filtering out some jitter. But also give a slower response time to changes on the input. For a joystick you may even select a higher value. Do some testing and find a value that you are happy with
 

THE_RB

Joined Feb 11, 2008
5,438
The cap is best placed close to the PIC ADC input pin.

The resistance of the pot then gives you RC low-pass filtering so you won't get any high freq noise at the ADC input.

And it's always a good idea to multi sample the ADC over time, then average the readings together (like we discussed in your other thread). That increases resolution and removes low freq noise (like mains hum).
:)
 

MrChips

Joined Oct 2, 2009
30,821
Just so that you know, when doing signal averaging, if your samples are equally spaced in time and the total number of samples span one full AC mains cycle or any multiple of full cycles, you can significantly reduce AC mains noise.
 
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